Otitis media with effusion (OME) is both extremely common in young children, and variable in its duration and severity. This study aims to gather and consider new and reliable information about the incidence and prevalence of OME in British school children. Eight hundred and fifty-six school children aged five to eight years from four South West Hampshire schools were examined over a three-year period by tympanometry, a method used to detect OME (> 90 per cent specificity and sensitivity) performed once per school term. Normal ears were recorded in 54.9 per cent of children throughout with 27 per cent recording evidence of effusion. However in only one out of 10 of the affected children did the fluid persist for a year or more. This impressive clearance is due in part to natural resolution, with the intervention of surgery occurring in about one in eight of the children with identified effusions. OME is more common in five-year-olds with an annual prevalence of 17 per cent compared to six per cent in eight-year-olds and is more common in the winter months. Because of the variability of the condition at least two screenings are recommended as a basis for good management.